.\" $OpenBSD: CMS_add1_recipient_cert.3,v 1.7 2019/11/02 15:39:46 schwarze Exp $
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.Dd $Mdocdate: November 2 2019 $
.Dt CMS_ADD1_RECIPIENT_CERT 3
.Os
.Sh NAME
.Nm CMS_add1_recipient_cert ,
.Nm CMS_add0_recipient_key
.Nd add recipients to a CMS EnvelopedData structure
.Sh SYNOPSIS
.In openssl/cms.h
.Ft CMS_RecipientInfo *
.Fo CMS_add1_recipient_cert
.Fa "CMS_ContentInfo *cms"
.Fa "X509 *certificate"
.Fa "unsigned int flags"
.Fc
.Ft CMS_RecipientInfo *
.Fo CMS_add0_recipient_key
.Fa "CMS_ContentInfo *cms"
.Fa "int nid"
.Fa "unsigned char *key"
.Fa "size_t keylen"
.Fa "unsigned char *id"
.Fa "size_t idlen"
.Fa "ASN1_GENERALIZEDTIME *date"
.Fa "ASN1_OBJECT *otherTypeId"
.Fa "ASN1_TYPE *otherType"
.Fc
.Sh DESCRIPTION
These functions add a new
.Vt RecipientInfo
structure to the
.Fa recipientInfos
field of the
.Vt EnvelopedData
structure
.Fa cms ,
which should have been obtained from an initial call to
.Xr CMS_encrypt 3
with the flag
.Dv CMS_PARTIAL
set.
.Pp
.Fn CMS_add1_recipient_cert
adds the recipient
.Fa certificate
as a
.Vt KeyTransRecipientInfo
structure.
.Pp
.Fn CMS_add0_recipient_key
adds the symmetric
.Fa key
of length
.Fa keylen
using the wrapping algorithm
.Fa nid ,
the identifier
.Fa id
of length
.Fa idlen ,
and the optional values
.Fa date ,
.Fa otherTypeId
and
.Fa otherType
as a
.Vt KEKRecipientInfo
structure.
.Pp
The main purpose of these functions is to provide finer control over a CMS
.Vt EnvelopedData
structure where the simpler
.Xr CMS_encrypt 3
function defaults are not appropriate,
for example if one or more
.Vt KEKRecipientInfo
structures need to be added.
New attributes can also be added using the returned
.Vt CMS_RecipientInfo
structure and the CMS attribute utility functions.
.Pp
By default, recipient certificates are identified using issuer
name and serial number.
If the flag
.Dv CMS_USE_KEYID
is set, the subject key identifier value is used instead.
An error occurs if all recipient certificates do not have a subject key
identifier extension.
.Pp
Currently only AES based key wrapping algorithms are supported for
.Fa nid ,
specifically
.Dv NID_id_aes128_wrap ,
.Dv NID_id_aes192_wrap ,
and
.Dv NID_id_aes256_wrap .
If
.Fa nid
is set to
.Dv NID_undef ,
then an AES wrap algorithm will be used consistent with
.Fa keylen .
.Sh RETURN VALUES
.Fn CMS_add1_recipient_cert
and
.Fn CMS_add0_recipient_key
return an internal pointer to the
.Vt CMS_RecipientInfo
structure just added or
.Dv NULL
if an error occurs.
.Sh SEE ALSO
.Xr CMS_ContentInfo_new 3 ,
.Xr CMS_encrypt 3 ,
.Xr CMS_final 3 ,
.Xr ERR_get_error 3
.Sh STANDARDS
RFC 5652: Cryptographic Message Syntax
.Bl -dash -compact -offset indent
.It
section 6.1: EnvelopedData Type
.It
section 6.2.1: KeyTransRecipientInfo Type
.It
section 6.2.3: KEKRecipientInfo Type
.El
.Sh HISTORY
.Fn CMS_add1_recipient_cert
and
.Fn CMS_add0_recipient_key
first appeared in OpenSSL 0.9.8h
and have been available since
.Ox 6.7 .
